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[Interarm blood pressure difference: Concordance between two methods of automatic simultaneous measurement and
Nuria Martínez-Sánchez1, Antonio Palasí2, Guillem Pera3
1Centro de Atención Primaria Parets, Institut Català de la Salut, Parets del Vallès, Barcelona, España.
Objective:
An increased interarm blood pressure difference (IAD) (≥10mmHg) has been associated with increased cardiovascular morbidity and mortality. There are few studies determining how IAD has to be measured and its reliability between visits. The objectives of our study were twofold. First, to evaluate the concordance between two automatic oscillometric devices for IAD measurement (two OMRON devices and one Microlife WatchBP™ device (WBP™)) and to analyse the reproducibility of IAD between visits in the general population attending a primary care centre.
Design:
Descriptive cross-sectional study of concordance between the two methods and reproducibility of IAD between two visits separated by one week. SITE: Parets del Vallès primary care centre (Barcelona).
Participants:
General population aged 35-74 years.
Interventions And Main Measurements:
One hundred and forty-nine patients completed the two visits. At each visit, IAD was measured three times with both methods and the mean of the three determinations was considered. Other variables such as sociodemographic and anthropometric variables, pathological antecedents and pharmacological treatment were collected through a review of the medical history and an interview with the patient. Concordance between the two devices and between visits reproducibility were calculated using the Lin concordance coefficient (CCL) for IAD expressed continuously and kappa(k) indices for IAD categorised as normal or pathological.
Results:
Concordance for IAD expressed continuously was low: CCL=0.13 (0.02-0.24). Concordance was also low for IAD categorised as normal or pathological (k=-0.03 (-0.05-0.00)). Reproducibility between visits was low for both methods and for both continuous and categorised IAD: with OMRON™ CCL=0.19 (0.03-0.34) and k=-0.02 (-0.16-0.12) and for WBP™ CCL=0.14 (-0.01-0.29) and k=0.49 (0.33-0.64).
Conclusions:
Concordance between two automatic oscillometers in the simultaneous IAD measurement was low. Reproducibility between visits was also low for both methods.
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